Ok, I'll correct you. You're wrong. You can open any book in Safari and transfer it to iBooks, Marvin, Kindle, or whatever eBook reader you want to use. ....

Ok, would really like to know how to open an ebook bought from Amazon, Barnes & Noble, Apple, etc. or an online ebook rental from your local Library in Safari without using their specified app and then move it to whichever reader app you want to use and without circumventing the DRM contained in each of those formats.

I cannot be held responsible for the things that come out of my mouth.
In the Windows world, most everything folks don't understand is called a virus.